Ask a landlord-tenant lawyer and get answers ASAP
Legally, he is considered a month to month tenant even where not paying rent. You give 30 day notice to end that tenancy and then may file in court. Practically, it can be expedited by negotiating to have him leave in exchange for helping him with moving, or having a lawyer file for eviction to add more pressure and leverage to the eviction.
Please let me know if that is clear and helpful.